Electric valve converting apparatus



1937- I R. c. GRIFFITH ET AL 2,099,561

ELECTRIC VALVE CONVERTING APPARATUS Original Filed Nov. 25, 1953 Invent0P5:

ROI land C. Griffith, Burnice D. ge dford.

Their" Attorney.

can

arc. fhowever, has not been directly applicable to a system employing aplurality of vapor electric apparatus with independent cathodepotentials. "Our present invention, while of a general application, isprimarily directed to such a system "employing a plurality of singleanode vapor electric apparatus with independent cathode poten- *tials..It is an object of our invention, therefore,fto 40 verting system inwhich the operation of the "apparatus will be controlled in response to*the {occurrence of actual or incipient reverse ,arcs within.theapparatus. v It" is another object of our invention to provide animproved vapor electric valve converting sys- Patent ed Nov. 16, 1937UNITED STATES PATENT OFFICE 2,099,561 ELECTRIC VALVE CONVERTINGAPPARATUSRolland C. Griffith and Burnice 1).;Bedfoid, Schenectady, N. Y.,assignors to Gcneral Electric Company, a corporatioriof New YorkApplication November 25,1933; Serial No; 699,758

Renewed June-:12, 1937 reverse arcs generally appear as arcs between theseveral anodes of a multi-anode vapor electric apparatus; or as areverse are from the cathode tothe anode of a single-anode vaporelectric apparatus operating in a system utilizfing'a'number of suchapparatus -Ifrsuch reverse '-arcs within the vapor electric apparatusarea;-

lowed to-persist they may cause serious damage,

notonly-to'the apparatus itself, but to the 'tem and other apparatuswith which the;va por electric apparatus is associated. It'hasjheretoffore been proposed to control the -ope'ratio'n of such vaporelectric apparatus of the metal tank type by providing theanodes of theapparatus with associated control .grids and controlling the potentialof these grids in response to thereversal of the potential between thecathode and the metal tank, which, it has been discovered, is

an indication of an actual or incipient reverse This arrangement aspreviously devised,

provide an improved vapor electric valve-contem in which the controlelectrodes associated "with the several anodes of the converting appa-Iratus are normally excited with a control poten- "and in which thiscontrolling potential is suppressed in response to the occurrence ofincipient or actual reverse arcs within the apparatus. 1

tial to control the conductivity of the apparatus In accordance with oneembodiment of ourfin- -vention', the several anodes of a vapor electricanparatus of a valve converting system are pro- 'vided with associatedcontrol electrodes upon which are impressed control potentials fornormally controlling the conductivity of the apparatus' Also enclosedwithin the separate container of each vapor electric apparatus is anauxiliary conductive electrode, or member, in contact with the ionizedvapor. In the case of an apparatus with a metallic container, thismember may comprise the container itself. This conductive memberisconnected to its respective cathode through a unilaterally conductivedevice and an insulating transformer. The secondary windings of theseveral insulating transformers are connected to the common controlcircuit of an auxiliar'y electric-valve which is connected to modifythe-magnetization; as for example, by saturation,

of the main' control transformer. In this manner, the" occurrence of areverse are within any of the vaporelectric apparatus reverses the pojtential between its auxiliary conductive member and its cathode, sendingan impulse of current through its associated transformer which iseffective to render conductive the'auxiliary electric valve tosaturatethe main control transformers and thus to remove the excitationand render the main valve converting apparatus nonconductive. Fora-bette'r understanding of our invention, together with other andfurther objects thereof, reference is had to the following descriptiontaken 'in connection with the accompanying drawing, '1 andits scope willbe pointed out in the appended "claims." The'singlefigure of the drawingis a diagrammatic representation of our invention as applied to theprotection from reverse arcs of a yapor electric 'valve convertingsystem for transmitting energy from a three phase alternating currentsupply circuit to a direct current load circuit.

1"Referring now more particularly to the drawing, there'is'shown a vaporelectric valve converting systemembodying our invention for transmittingenergy from a three phase alternat- A= current smoothing reactor I1 isvided with an anode, a cathode, a control grid, and an auxiliaryconductive member or electrode [8 in contact with the ionized vapor ofthe valve, although, as stated above, in case the valve is containedwithin a metallic envelope, the envelope itself may constitute theauxiliary conductive member. The control electrodes of the electricvalves l4, l5 and I6 are connected to their common cathode circuitthrough protective resistors 19, negative bias batteries 20, and thesecondary windings of the main control transformers 2|, 22 and 23,respectively. The main control transformers 2l-23, inc., may be of anydesired type, although we prefer to use selfsaturating transformers, sothat the potentials induced in the secondary windings are of peaked waveform. The primary windings of these transformers are energized from theappropriate phases of the supply circuit I through any suitable phaseadjusting mechanism, such as a rotary phase shifting transformer 24.

In order to render ineffective the normal excitation circuit for thecontrol electrodes of the several electric valves under reverse arcconditions, the auxiliary conductive members [8 of the electric valvesl4-l5-I6 are connected to their respective cathodes through unilaterallyconductive devices, such as contact rectifiers 25-26-21 and the primarywindings of auxiliary control transformers 28-29-30, respectively. Thesecondary windings of the transformers 28-29-30 are connected inparallel through protective resistors 3i and to the control electrode ofan auxiliary electric valve 32. This common control circuit may includealso a biasing battery 33, if desired. Each of the main controltransformers 2 l-22-23 is provided with an auxiliary saturating winding34, and these windings are connected to be excited in series from asource of current, such as a battery 35, through the auxiliary electricvalve 32. Switching means shown as a manually operated switch 36 may beprovided to interrupt the current in the saturating windings 34 andrestore the operation of the system.

The general principles of operation of the above described rectifyingsystem will be well understood by those skilled in the art, so that adetailed description is believed to be unnecessary. It will also be wellunderstood that the average energy supplied to the load circuit ll maybe controlled by adjusting the rotary phase shifting transformer 24 toadjust the phase relationship between the alternating potentialsimpressed upon the control electrodes of the electric valves I4-I5-l6and the anode potentials of these valves. If it be assumed, for example,that at any particular instant the electric valve I is operatingnormally as a rectifying valve, and electric valve l4 fails, so that areverse arc tends to flow from its cathode to its anode, it will be seenthat two of the phases of the network l3 tend to become short circuitedthrough the electric valves l5 and M in series. As stated above, it hasbeen demonstrated that under such condi tions, the potential of theauxiliary conductive electrode l8 with respect to the cathode of theelectrode valve l4 reverses in potential from a normally positive valueto a negative value. This reversal may take place upon the occurrence ofan incipient are back which may actually never develop into a power arc.The unilaterally conductive devices 25-26-21 are so connected that, withnormal potential impressed upon the auxiliary electrodes l8, no currentflows in the primary windings of the auxiliary control transformers28-29-30. Upon the reversal of potential between the electrode l3 of thevalve I4 and its cathode, however, a current impulse is sent through theprimary winding of the transformer 28 which impresses a positive impulseon the auxiliary electric valve 32 to render this valve conductive. Inthis manner, the source of current 35 is effective to energize thesaturating windings 34 of the main control transformers 2l-22-23 tocompletely suppress the potentials normally induced in the secondarywindings of these transformers. The result is, that the negative biasbatteries in the control circuits of the electric valves l4-l5-l6 areeffective to render these valves nonconductive. Valve 32 is preferablyof the vapor electric discharge type so that it will maintain thetransformers 2l-22-23 in a saturated condition until the circuit oftheir saturating windings is opened by the switch 35. In this way anincipient or actual reverse arc in any of the several electric valvesi4-l5-l6 is effective to interrupt the operation of the system and thusprevent damage to the system and its associated apparatus.

While we have described What we at present consider the preferredembodiment of our invention, it will be obvious to those skilled in theart that various changes and modifications may be made without departingfrom our invention, and we, therefore, aim in the appended claims tocover all such changes and modifications as fall within the true spiritand scope of our invention.

What we claim as new and desire to secure by Letters Patent of theUnited States, is:

1. In combination with a vapor electric valve converting apparatuscomprising an anode, a cathode, a control electrode, and a conductivemember in contact with the ionized vapor of the apparatus, a saturablecontrol transformer for exciting said control electrode to control theenergy transmitted by said apparatus, and means responsive to thepotential between said conductive member and said cathode for varyingthe saturation of said transformer to control the energy transmitted bysaid apparatus.

2. In combination with a vapor electric valve converting apparatuscomprising an anode, a cathode, a control electrode, and a conductivemember in contact with the ionized vapor of the apparatus, a saturablecontrol transformer for exciting said control electrode to control theenergy transmitted by said apparatus, and means responsive to a reversalof the potential between said conductive member and said cathode forsaturating said control transformer to suppress the excitation to saidcontrol electrode and to render said valve apparatus nonconductive.

3. In combination with a vapor electric valve converting apparatuscomprising an anode, a cathode, a control electrode, and a conductivemember in contact with the ionized vapor of the apparatus, an excitationcircuit for said control electrode including a source of negative biaspotential, a self saturatingtransformer provided. with a windingincluded in said control circuit to impress upon said control electrodean alternating potential of peaked wave form for normally controllingthe conductivity of said apparatus, and means responsive to a reversalof the potential between said conductive member and said cathode uponthe occurrence of a reverse arc in said apparatus for saturating saidtransformer to suppress the excitation to said control electrode and torender said apparatus nonconductive.

4. In combination with a vapor electric valve converting apparatuscomprising an anode, a cathode, a control electrode, and a conductivemember in contact with the ionized vapor of the apparatus, a controltransformer for exciting said control electrode to control the energytransmitted by said apparatus, a saturating winding for saidtransformer, means including an auxiliary electric valve for controllingenergization of said saturating winding, and means responsive to thepotential between said conductive member and said cathode forcontrolling the conductivity of said auxiliary valve.

5. In combination with a vapor electric valve converting apparatuscomprising an anode, a cathode, a control electrode, and a conductivemember in contact with the ionized vapor of the apparatus, a controltransformer for exciting said control electrode to control the energytransmitted by said apparatus, a saturating Winding for saidtransformer, an energizing circuit for said saturating winding includingan auxiliary electric valve, and means responsive to a reversal ofpotential between said conductive member and said cathode upon theoccurrence of a reverse arc in said apparatus for rendering conductivesaid auxiliary electric valve, whereby said vapor electric apparatus isrendered nonconductive.

6. In an electric valve converting system, a plurality of electricvalves each provided with an anode, a cathode, a control electrode, anda conductive member in contact with the ionized vapor of the apparatus,control transformer apparatus connected to excite the control electrodesof'said valves to normally control their conductivity, an auxiliarycontrol circuit interconnecting the conductive member and the cathode ofeach of said valves, and a circuit for saturating said control apparatusincluding an auxiliary electric valve, said auxiliary electric valvebeing connected to respond to the reversal of potential in anyof saidcontrol circuits.

7. In an electric valve converting system, a plurality of electricvalves each provided with an anode, a cathode, a control electrode, anda conductive member in contact with the ionized vapor of the apparatus,an exciting circuit for the control electrode of each of said valves,each including a saturable transformer for normally controlling theconductivity of its associated valve, an auxiliary control circuitinterconnecting the conductive member and the cathode of each of saidvalves including a unilaterally conductive device, and a circuit forsaturating said transformers including an auxiliary electric valve, saidauxiliary electric valve being connected to be excited by the flow ofcurrent in any of said auxiliary control circuits.

ROLLAND C. GRIFFITH. BURNICE D. BEDFORD.

